A combined group of scientists from Unilever Research, the UK University of Exeter and Plant Research International in the Netherlands have produced transgenic tomato lines which have as much as an 78-fold increase of fruit peel flavonols, mainly due to the accumulation of rutin, Reading Scientific Services reports. Flavonols are important antioxidants which epidemiological data suggest may have a role in reducing the risk of cardiovascular disease. The tomato is already established as a source of lycopene, a carotenoid which may be protective against prostate cancer. However, tomato peel contains flavonoids (5-10 mg/kg fresh weight) including naringenin chalcone and the flavonol rutin, a quercetin glycoside. The two flavonols quercetin and kaempferol appear to show particularly good cardiovascular protective effects so the development of transgenic plants rich in such compounds could have obvious health benefits. In the present study constitutive overexpression of a Petunia gene encoding chalcone isomerase (CHI) in tomato resulted in elevated flavonol end products in the fruit peel. The tomato lines contained significantly increased levels of quercetin glycosides, and smaller but still substantial increases in kaempferol glycosides in fruit peel. Processing of the high-flavonol tomatoes into tomato paste showed that 65 per cent of the flavonols present in the fresh fruit were retained in the processsed product, making them suitable as raw materials for tomato-based functional foods. Source: Nature Biotechnology 2001: 19 (5), 470-47 and Reading Scientific Services.